On Thu, 2006-04-20 at 14:33 -0700, Eugene Surovegin wrote: > On Fri, Apr 21, 2006 at 07:06:13AM +1000, Benjamin Herrenschmidt wrote: > > (On 6xx this is deadly even if you don't access those cacheable pages > > because the CPU prefetch may do it for you). > > Here is another thought if this "prefetch" theory is correct. > > You guys seems to focus on > dma_alloc_coherent()/pci_alloc_consistent(), but forgeting about so > called "streaming" mappings. > > You cannot just flush/invalidate cache any more, because "CPU can > prefetch this data back". So, to be completely correct (if you insist > on "6xx can prefetch"-theory), you have to actually _copy_ data to > your consistent memory on dma_map_single(). You can imagine > performance implications. I suspect even 440 will be faster in this > case than G4 :).
Yes. Ben. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
